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1 | /* |
2 | * This file is subject to the terms and conditions of the GNU General Public | |
3 | * License. See the file "COPYING" in the main directory of this archive | |
4 | * for more details. | |
5 | * | |
6 | * Unified implementation of memcpy, memmove and the __copy_user backend. | |
7 | * | |
8 | * Copyright (C) 1998, 99, 2000, 01, 2002 Ralf Baechle (ralf@gnu.org) | |
9 | * Copyright (C) 1999, 2000, 01, 2002 Silicon Graphics, Inc. | |
10 | * Copyright (C) 2002 Broadcom, Inc. | |
11 | * memcpy/copy_user author: Mark Vandevoorde | |
12 | * | |
13 | * Mnemonic names for arguments to memcpy/__copy_user | |
14 | */ | |
15 | ||
16 | #include <asm/asm.h> | |
17 | #include <asm/asm-offsets.h> | |
18 | #include <asm/regdef.h> | |
19 | ||
20 | #define dst a0 | |
21 | #define src a1 | |
22 | #define len a2 | |
23 | ||
24 | /* | |
25 | * Spec | |
26 | * | |
27 | * memcpy copies len bytes from src to dst and sets v0 to dst. | |
28 | * It assumes that | |
29 | * - src and dst don't overlap | |
30 | * - src is readable | |
31 | * - dst is writable | |
32 | * memcpy uses the standard calling convention | |
33 | * | |
34 | * __copy_user copies up to len bytes from src to dst and sets a2 (len) to | |
35 | * the number of uncopied bytes due to an exception caused by a read or write. | |
36 | * __copy_user assumes that src and dst don't overlap, and that the call is | |
37 | * implementing one of the following: | |
38 | * copy_to_user | |
39 | * - src is readable (no exceptions when reading src) | |
40 | * copy_from_user | |
41 | * - dst is writable (no exceptions when writing dst) | |
42 | * __copy_user uses a non-standard calling convention; see | |
43 | * arch/mips/include/asm/uaccess.h | |
44 | * | |
45 | * When an exception happens on a load, the handler must | |
46 | # ensure that all of the destination buffer is overwritten to prevent | |
47 | * leaking information to user mode programs. | |
48 | */ | |
49 | ||
50 | /* | |
51 | * Implementation | |
52 | */ | |
53 | ||
54 | /* | |
55 | * The exception handler for loads requires that: | |
56 | * 1- AT contain the address of the byte just past the end of the source | |
57 | * of the copy, | |
58 | * 2- src_entry <= src < AT, and | |
59 | * 3- (dst - src) == (dst_entry - src_entry), | |
60 | * The _entry suffix denotes values when __copy_user was called. | |
61 | * | |
62 | * (1) is set up up by uaccess.h and maintained by not writing AT in copy_user | |
63 | * (2) is met by incrementing src by the number of bytes copied | |
64 | * (3) is met by not doing loads between a pair of increments of dst and src | |
65 | * | |
66 | * The exception handlers for stores adjust len (if necessary) and return. | |
67 | * These handlers do not need to overwrite any data. | |
68 | * | |
69 | * For __rmemcpy and memmove an exception is always a kernel bug, therefore | |
70 | * they're not protected. | |
71 | */ | |
72 | ||
73 | #define EXC(inst_reg,addr,handler) \ | |
74 | 9: inst_reg, addr; \ | |
75 | .section __ex_table,"a"; \ | |
76 | PTR 9b, handler; \ | |
77 | .previous | |
78 | ||
79 | /* | |
80 | * Only on the 64-bit kernel we can made use of 64-bit registers. | |
81 | */ | |
82 | #ifdef CONFIG_64BIT | |
83 | #define USE_DOUBLE | |
84 | #endif | |
85 | ||
86 | #ifdef USE_DOUBLE | |
87 | ||
88 | #define LOAD ld | |
89 | #define LOADL ldl | |
90 | #define LOADR ldr | |
91 | #define STOREL sdl | |
92 | #define STORER sdr | |
93 | #define STORE sd | |
94 | #define ADD daddu | |
95 | #define SUB dsubu | |
96 | #define SRL dsrl | |
97 | #define SRA dsra | |
98 | #define SLL dsll | |
99 | #define SLLV dsllv | |
100 | #define SRLV dsrlv | |
101 | #define NBYTES 8 | |
102 | #define LOG_NBYTES 3 | |
103 | ||
104 | /* | |
105 | * As we are sharing code base with the mips32 tree (which use the o32 ABI | |
106 | * register definitions). We need to redefine the register definitions from | |
107 | * the n64 ABI register naming to the o32 ABI register naming. | |
108 | */ | |
109 | #undef t0 | |
110 | #undef t1 | |
111 | #undef t2 | |
112 | #undef t3 | |
113 | #define t0 $8 | |
114 | #define t1 $9 | |
115 | #define t2 $10 | |
116 | #define t3 $11 | |
117 | #define t4 $12 | |
118 | #define t5 $13 | |
119 | #define t6 $14 | |
120 | #define t7 $15 | |
121 | ||
122 | #else | |
123 | ||
124 | #define LOAD lw | |
125 | #define LOADL lwl | |
126 | #define LOADR lwr | |
127 | #define STOREL swl | |
128 | #define STORER swr | |
129 | #define STORE sw | |
130 | #define ADD addu | |
131 | #define SUB subu | |
132 | #define SRL srl | |
133 | #define SLL sll | |
134 | #define SRA sra | |
135 | #define SLLV sllv | |
136 | #define SRLV srlv | |
137 | #define NBYTES 4 | |
138 | #define LOG_NBYTES 2 | |
139 | ||
140 | #endif /* USE_DOUBLE */ | |
141 | ||
142 | #ifdef CONFIG_CPU_LITTLE_ENDIAN | |
143 | #define LDFIRST LOADR | |
144 | #define LDREST LOADL | |
145 | #define STFIRST STORER | |
146 | #define STREST STOREL | |
147 | #define SHIFT_DISCARD SLLV | |
148 | #else | |
149 | #define LDFIRST LOADL | |
150 | #define LDREST LOADR | |
151 | #define STFIRST STOREL | |
152 | #define STREST STORER | |
153 | #define SHIFT_DISCARD SRLV | |
154 | #endif | |
155 | ||
156 | #define FIRST(unit) ((unit)*NBYTES) | |
157 | #define REST(unit) (FIRST(unit)+NBYTES-1) | |
158 | #define UNIT(unit) FIRST(unit) | |
159 | ||
160 | #define ADDRMASK (NBYTES-1) | |
161 | ||
162 | .text | |
163 | .set noreorder | |
164 | .set noat | |
165 | ||
166 | /* | |
167 | * A combined memcpy/__copy_user | |
168 | * __copy_user sets len to 0 for success; else to an upper bound of | |
169 | * the number of uncopied bytes. | |
170 | * memcpy sets v0 to dst. | |
171 | */ | |
172 | .align 5 | |
173 | LEAF(memcpy) /* a0=dst a1=src a2=len */ | |
174 | move v0, dst /* return value */ | |
175 | __memcpy: | |
176 | FEXPORT(__copy_user) | |
177 | /* | |
178 | * Note: dst & src may be unaligned, len may be 0 | |
179 | * Temps | |
180 | */ | |
181 | # | |
182 | # Octeon doesn't care if the destination is unaligned. The hardware | |
183 | # can fix it faster than we can special case the assembly. | |
184 | # | |
185 | pref 0, 0(src) | |
186 | sltu t0, len, NBYTES # Check if < 1 word | |
187 | bnez t0, copy_bytes_checklen | |
188 | and t0, src, ADDRMASK # Check if src unaligned | |
189 | bnez t0, src_unaligned | |
190 | sltu t0, len, 4*NBYTES # Check if < 4 words | |
191 | bnez t0, less_than_4units | |
192 | sltu t0, len, 8*NBYTES # Check if < 8 words | |
193 | bnez t0, less_than_8units | |
194 | sltu t0, len, 16*NBYTES # Check if < 16 words | |
195 | bnez t0, cleanup_both_aligned | |
196 | sltu t0, len, 128+1 # Check if len < 129 | |
197 | bnez t0, 1f # Skip prefetch if len is too short | |
198 | sltu t0, len, 256+1 # Check if len < 257 | |
199 | bnez t0, 1f # Skip prefetch if len is too short | |
200 | pref 0, 128(src) # We must not prefetch invalid addresses | |
201 | # | |
202 | # This is where we loop if there is more than 128 bytes left | |
203 | 2: pref 0, 256(src) # We must not prefetch invalid addresses | |
204 | # | |
205 | # This is where we loop if we can't prefetch anymore | |
206 | 1: | |
207 | EXC( LOAD t0, UNIT(0)(src), l_exc) | |
208 | EXC( LOAD t1, UNIT(1)(src), l_exc_copy) | |
209 | EXC( LOAD t2, UNIT(2)(src), l_exc_copy) | |
210 | EXC( LOAD t3, UNIT(3)(src), l_exc_copy) | |
211 | SUB len, len, 16*NBYTES | |
212 | EXC( STORE t0, UNIT(0)(dst), s_exc_p16u) | |
213 | EXC( STORE t1, UNIT(1)(dst), s_exc_p15u) | |
214 | EXC( STORE t2, UNIT(2)(dst), s_exc_p14u) | |
215 | EXC( STORE t3, UNIT(3)(dst), s_exc_p13u) | |
216 | EXC( LOAD t0, UNIT(4)(src), l_exc_copy) | |
217 | EXC( LOAD t1, UNIT(5)(src), l_exc_copy) | |
218 | EXC( LOAD t2, UNIT(6)(src), l_exc_copy) | |
219 | EXC( LOAD t3, UNIT(7)(src), l_exc_copy) | |
220 | EXC( STORE t0, UNIT(4)(dst), s_exc_p12u) | |
221 | EXC( STORE t1, UNIT(5)(dst), s_exc_p11u) | |
222 | EXC( STORE t2, UNIT(6)(dst), s_exc_p10u) | |
223 | ADD src, src, 16*NBYTES | |
224 | EXC( STORE t3, UNIT(7)(dst), s_exc_p9u) | |
225 | ADD dst, dst, 16*NBYTES | |
226 | EXC( LOAD t0, UNIT(-8)(src), l_exc_copy) | |
227 | EXC( LOAD t1, UNIT(-7)(src), l_exc_copy) | |
228 | EXC( LOAD t2, UNIT(-6)(src), l_exc_copy) | |
229 | EXC( LOAD t3, UNIT(-5)(src), l_exc_copy) | |
230 | EXC( STORE t0, UNIT(-8)(dst), s_exc_p8u) | |
231 | EXC( STORE t1, UNIT(-7)(dst), s_exc_p7u) | |
232 | EXC( STORE t2, UNIT(-6)(dst), s_exc_p6u) | |
233 | EXC( STORE t3, UNIT(-5)(dst), s_exc_p5u) | |
234 | EXC( LOAD t0, UNIT(-4)(src), l_exc_copy) | |
235 | EXC( LOAD t1, UNIT(-3)(src), l_exc_copy) | |
236 | EXC( LOAD t2, UNIT(-2)(src), l_exc_copy) | |
237 | EXC( LOAD t3, UNIT(-1)(src), l_exc_copy) | |
238 | EXC( STORE t0, UNIT(-4)(dst), s_exc_p4u) | |
239 | EXC( STORE t1, UNIT(-3)(dst), s_exc_p3u) | |
240 | EXC( STORE t2, UNIT(-2)(dst), s_exc_p2u) | |
241 | EXC( STORE t3, UNIT(-1)(dst), s_exc_p1u) | |
242 | sltu t0, len, 256+1 # See if we can prefetch more | |
243 | beqz t0, 2b | |
244 | sltu t0, len, 128 # See if we can loop more time | |
245 | beqz t0, 1b | |
246 | nop | |
247 | # | |
248 | # Jump here if there are less than 16*NBYTES left. | |
249 | # | |
250 | cleanup_both_aligned: | |
251 | beqz len, done | |
252 | sltu t0, len, 8*NBYTES | |
253 | bnez t0, less_than_8units | |
254 | nop | |
255 | EXC( LOAD t0, UNIT(0)(src), l_exc) | |
256 | EXC( LOAD t1, UNIT(1)(src), l_exc_copy) | |
257 | EXC( LOAD t2, UNIT(2)(src), l_exc_copy) | |
258 | EXC( LOAD t3, UNIT(3)(src), l_exc_copy) | |
259 | SUB len, len, 8*NBYTES | |
260 | EXC( STORE t0, UNIT(0)(dst), s_exc_p8u) | |
261 | EXC( STORE t1, UNIT(1)(dst), s_exc_p7u) | |
262 | EXC( STORE t2, UNIT(2)(dst), s_exc_p6u) | |
263 | EXC( STORE t3, UNIT(3)(dst), s_exc_p5u) | |
264 | EXC( LOAD t0, UNIT(4)(src), l_exc_copy) | |
265 | EXC( LOAD t1, UNIT(5)(src), l_exc_copy) | |
266 | EXC( LOAD t2, UNIT(6)(src), l_exc_copy) | |
267 | EXC( LOAD t3, UNIT(7)(src), l_exc_copy) | |
268 | EXC( STORE t0, UNIT(4)(dst), s_exc_p4u) | |
269 | EXC( STORE t1, UNIT(5)(dst), s_exc_p3u) | |
270 | EXC( STORE t2, UNIT(6)(dst), s_exc_p2u) | |
271 | EXC( STORE t3, UNIT(7)(dst), s_exc_p1u) | |
272 | ADD src, src, 8*NBYTES | |
273 | beqz len, done | |
274 | ADD dst, dst, 8*NBYTES | |
275 | # | |
276 | # Jump here if there are less than 8*NBYTES left. | |
277 | # | |
278 | less_than_8units: | |
279 | sltu t0, len, 4*NBYTES | |
280 | bnez t0, less_than_4units | |
281 | nop | |
282 | EXC( LOAD t0, UNIT(0)(src), l_exc) | |
283 | EXC( LOAD t1, UNIT(1)(src), l_exc_copy) | |
284 | EXC( LOAD t2, UNIT(2)(src), l_exc_copy) | |
285 | EXC( LOAD t3, UNIT(3)(src), l_exc_copy) | |
286 | SUB len, len, 4*NBYTES | |
287 | EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) | |
288 | EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) | |
289 | EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) | |
290 | EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) | |
291 | ADD src, src, 4*NBYTES | |
292 | beqz len, done | |
293 | ADD dst, dst, 4*NBYTES | |
294 | # | |
295 | # Jump here if there are less than 4*NBYTES left. This means | |
296 | # we may need to copy up to 3 NBYTES words. | |
297 | # | |
298 | less_than_4units: | |
299 | sltu t0, len, 1*NBYTES | |
300 | bnez t0, copy_bytes_checklen | |
301 | nop | |
302 | # | |
303 | # 1) Copy NBYTES, then check length again | |
304 | # | |
305 | EXC( LOAD t0, 0(src), l_exc) | |
306 | SUB len, len, NBYTES | |
307 | sltu t1, len, 8 | |
308 | EXC( STORE t0, 0(dst), s_exc_p1u) | |
309 | ADD src, src, NBYTES | |
310 | bnez t1, copy_bytes_checklen | |
311 | ADD dst, dst, NBYTES | |
312 | # | |
313 | # 2) Copy NBYTES, then check length again | |
314 | # | |
315 | EXC( LOAD t0, 0(src), l_exc) | |
316 | SUB len, len, NBYTES | |
317 | sltu t1, len, 8 | |
318 | EXC( STORE t0, 0(dst), s_exc_p1u) | |
319 | ADD src, src, NBYTES | |
320 | bnez t1, copy_bytes_checklen | |
321 | ADD dst, dst, NBYTES | |
322 | # | |
323 | # 3) Copy NBYTES, then check length again | |
324 | # | |
325 | EXC( LOAD t0, 0(src), l_exc) | |
326 | SUB len, len, NBYTES | |
327 | ADD src, src, NBYTES | |
328 | ADD dst, dst, NBYTES | |
329 | b copy_bytes_checklen | |
330 | EXC( STORE t0, -8(dst), s_exc_p1u) | |
331 | ||
332 | src_unaligned: | |
333 | #define rem t8 | |
334 | SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter | |
335 | beqz t0, cleanup_src_unaligned | |
336 | and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES | |
337 | 1: | |
338 | /* | |
339 | * Avoid consecutive LD*'s to the same register since some mips | |
340 | * implementations can't issue them in the same cycle. | |
341 | * It's OK to load FIRST(N+1) before REST(N) because the two addresses | |
342 | * are to the same unit (unless src is aligned, but it's not). | |
343 | */ | |
344 | EXC( LDFIRST t0, FIRST(0)(src), l_exc) | |
345 | EXC( LDFIRST t1, FIRST(1)(src), l_exc_copy) | |
346 | SUB len, len, 4*NBYTES | |
347 | EXC( LDREST t0, REST(0)(src), l_exc_copy) | |
348 | EXC( LDREST t1, REST(1)(src), l_exc_copy) | |
349 | EXC( LDFIRST t2, FIRST(2)(src), l_exc_copy) | |
350 | EXC( LDFIRST t3, FIRST(3)(src), l_exc_copy) | |
351 | EXC( LDREST t2, REST(2)(src), l_exc_copy) | |
352 | EXC( LDREST t3, REST(3)(src), l_exc_copy) | |
353 | ADD src, src, 4*NBYTES | |
354 | EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) | |
355 | EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) | |
356 | EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) | |
357 | EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) | |
358 | bne len, rem, 1b | |
359 | ADD dst, dst, 4*NBYTES | |
360 | ||
361 | cleanup_src_unaligned: | |
362 | beqz len, done | |
363 | and rem, len, NBYTES-1 # rem = len % NBYTES | |
364 | beq rem, len, copy_bytes | |
365 | nop | |
366 | 1: | |
367 | EXC( LDFIRST t0, FIRST(0)(src), l_exc) | |
368 | EXC( LDREST t0, REST(0)(src), l_exc_copy) | |
369 | SUB len, len, NBYTES | |
370 | EXC( STORE t0, 0(dst), s_exc_p1u) | |
371 | ADD src, src, NBYTES | |
372 | bne len, rem, 1b | |
373 | ADD dst, dst, NBYTES | |
374 | ||
375 | copy_bytes_checklen: | |
376 | beqz len, done | |
377 | nop | |
378 | copy_bytes: | |
379 | /* 0 < len < NBYTES */ | |
380 | #define COPY_BYTE(N) \ | |
381 | EXC( lb t0, N(src), l_exc); \ | |
382 | SUB len, len, 1; \ | |
383 | beqz len, done; \ | |
384 | EXC( sb t0, N(dst), s_exc_p1) | |
385 | ||
386 | COPY_BYTE(0) | |
387 | COPY_BYTE(1) | |
388 | #ifdef USE_DOUBLE | |
389 | COPY_BYTE(2) | |
390 | COPY_BYTE(3) | |
391 | COPY_BYTE(4) | |
392 | COPY_BYTE(5) | |
393 | #endif | |
394 | EXC( lb t0, NBYTES-2(src), l_exc) | |
395 | SUB len, len, 1 | |
396 | jr ra | |
397 | EXC( sb t0, NBYTES-2(dst), s_exc_p1) | |
398 | done: | |
399 | jr ra | |
400 | nop | |
401 | END(memcpy) | |
402 | ||
403 | l_exc_copy: | |
404 | /* | |
405 | * Copy bytes from src until faulting load address (or until a | |
406 | * lb faults) | |
407 | * | |
408 | * When reached by a faulting LDFIRST/LDREST, THREAD_BUADDR($28) | |
409 | * may be more than a byte beyond the last address. | |
410 | * Hence, the lb below may get an exception. | |
411 | * | |
412 | * Assumes src < THREAD_BUADDR($28) | |
413 | */ | |
414 | LOAD t0, TI_TASK($28) | |
415 | nop | |
416 | LOAD t0, THREAD_BUADDR(t0) | |
417 | 1: | |
418 | EXC( lb t1, 0(src), l_exc) | |
419 | ADD src, src, 1 | |
420 | sb t1, 0(dst) # can't fault -- we're copy_from_user | |
421 | bne src, t0, 1b | |
422 | ADD dst, dst, 1 | |
423 | l_exc: | |
424 | LOAD t0, TI_TASK($28) | |
425 | nop | |
426 | LOAD t0, THREAD_BUADDR(t0) # t0 is just past last good address | |
427 | nop | |
428 | SUB len, AT, t0 # len number of uncopied bytes | |
429 | /* | |
430 | * Here's where we rely on src and dst being incremented in tandem, | |
431 | * See (3) above. | |
432 | * dst += (fault addr - src) to put dst at first byte to clear | |
433 | */ | |
434 | ADD dst, t0 # compute start address in a1 | |
435 | SUB dst, src | |
436 | /* | |
437 | * Clear len bytes starting at dst. Can't call __bzero because it | |
438 | * might modify len. An inefficient loop for these rare times... | |
439 | */ | |
440 | beqz len, done | |
441 | SUB src, len, 1 | |
442 | 1: sb zero, 0(dst) | |
443 | ADD dst, dst, 1 | |
444 | bnez src, 1b | |
445 | SUB src, src, 1 | |
446 | jr ra | |
447 | nop | |
448 | ||
449 | ||
450 | #define SEXC(n) \ | |
451 | s_exc_p ## n ## u: \ | |
452 | jr ra; \ | |
453 | ADD len, len, n*NBYTES | |
454 | ||
455 | SEXC(16) | |
456 | SEXC(15) | |
457 | SEXC(14) | |
458 | SEXC(13) | |
459 | SEXC(12) | |
460 | SEXC(11) | |
461 | SEXC(10) | |
462 | SEXC(9) | |
463 | SEXC(8) | |
464 | SEXC(7) | |
465 | SEXC(6) | |
466 | SEXC(5) | |
467 | SEXC(4) | |
468 | SEXC(3) | |
469 | SEXC(2) | |
470 | SEXC(1) | |
471 | ||
472 | s_exc_p1: | |
473 | jr ra | |
474 | ADD len, len, 1 | |
475 | s_exc: | |
476 | jr ra | |
477 | nop | |
478 | ||
479 | .align 5 | |
480 | LEAF(memmove) | |
481 | ADD t0, a0, a2 | |
482 | ADD t1, a1, a2 | |
483 | sltu t0, a1, t0 # dst + len <= src -> memcpy | |
484 | sltu t1, a0, t1 # dst >= src + len -> memcpy | |
485 | and t0, t1 | |
486 | beqz t0, __memcpy | |
487 | move v0, a0 /* return value */ | |
488 | beqz a2, r_out | |
489 | END(memmove) | |
490 | ||
491 | /* fall through to __rmemcpy */ | |
492 | LEAF(__rmemcpy) /* a0=dst a1=src a2=len */ | |
493 | sltu t0, a1, a0 | |
494 | beqz t0, r_end_bytes_up # src >= dst | |
495 | nop | |
496 | ADD a0, a2 # dst = dst + len | |
497 | ADD a1, a2 # src = src + len | |
498 | ||
499 | r_end_bytes: | |
500 | lb t0, -1(a1) | |
501 | SUB a2, a2, 0x1 | |
502 | sb t0, -1(a0) | |
503 | SUB a1, a1, 0x1 | |
504 | bnez a2, r_end_bytes | |
505 | SUB a0, a0, 0x1 | |
506 | ||
507 | r_out: | |
508 | jr ra | |
509 | move a2, zero | |
510 | ||
511 | r_end_bytes_up: | |
512 | lb t0, (a1) | |
513 | SUB a2, a2, 0x1 | |
514 | sb t0, (a0) | |
515 | ADD a1, a1, 0x1 | |
516 | bnez a2, r_end_bytes_up | |
517 | ADD a0, a0, 0x1 | |
518 | ||
519 | jr ra | |
520 | move a2, zero | |
521 | END(__rmemcpy) |